| 摘要 |
PURPOSE: To enable adjustment of a light color point of light that a lamp emits at a prescribed luminous flux by providing a circuit for adjusting a modulation frequency. CONSTITUTION: A circuit provided with a circuit I for generating a high-frequency pulse-shaped current having an amplitude from a power voltage and a modulator II for modulating a high-frequency pulse shaped current in a substantially rectangular wave shape at a modulation frequency and at a duty cycle and suitable to turn on a low-pressure mercury discharge by the high-frequency pulse shaped current, wherein a modulation frequency is adjusted by a modulation frequency adjustment circuit VI. Thereby, a light color point of light to be emitted from the lamp IV can be adjusted over a possibly wide range at a prescribed luminous flux. When this circuit is provided with the circuit III for adjusting an amplitude of the modulated frequency pulse shaped current, in case that a luminous flux of the lamp IV is set to a constant value, a range in which the light color point can be adjusted can be increased and brings advantageous result. |
